1. Field of the Invention
The present invention relates to a vehicle customizing system having control units as vehicle-mounted controllers for performing vehicle functions, e.g., a function to energize a passenger compartment lamp for a predetermined period of time when a vehicle door is unlocked, based on control characteristic values such as a setting of 15 seconds, 30 seconds, or 0 seconds (not energized), and a display unit, such as a multi-display unit, connected to the control unit through a communication line and having an input means for changing such control characteristic values.
2. Description of the Related Art
In recent years, a wide variety of motor vehicle equipment improvements have been made in the art, and modern motor vehicles incorporate control units for performing various vehicle functions based on control characteristic values, e.g., functions for electric accessories such as power window systems, air-conditioning units, etc., as well as functions for basic vehicle components such as the engine, steering system, brake system, etc., for propelling, turning and stopping the motor vehicle.
According to conventional vehicle control systems, control characteristic values for certain functions performed by control units can be changed by the user to desired values through a display screen meter unit provided on the instrumental panel, or through a navigation system display screen (see Japanese Laid-Open Patent Publication No. 10-264739 and Japanese Laid-Open Patent Publication No. 2002-12099 for details).
Japanese Laid-Open Patent Publication No. 10-264739 discloses a technique for changing control characteristic value settings for a transmission computer, making up a control unit connected to a communication line, using a multi-display unit including a vehicle display monitor and a multi-display computer.
Japanese Laid-Open Patent Publication No. 2002-12099 discloses a customizing apparatus for customizing functions of electrical accessories, including the air-conditioning unit, audio system, power window mechanism, etc., which are controlled by respective control units, based on control characteristic values preferred by the user, through a meter unit making up a display unit mounted on a motor vehicle, and depending on signals transmitted from a transmitter.
However, according to the conventional arrangements disclosed in Japanese Laid-Open Patent Publication No. 10-264739 and Japanese Laid-Open Patent Publication No. 2002-12099, the control characteristic values for the control units are stored in a memory (DVD or nonvolatile memory) within the display unit. When the control units on the motor vehicle are activated, e.g., when the ignition switch is turned on, or when the ignition switch is turned on and the switches of the control units are also turned on, the control characteristic values are read from the memory of the display unit, and then set in the various memories (volatile memories such as registers or RAMs) of the control units through a communication line. Thereafter, the functions of the control units can first be performed.
Consequently, it takes a certain period of time after the switches have been turned on in order to activate the control units and until the functions of the control units can be performed.
Further, if a communication failure occurs due to a communication line disconnection or the like, then since the control units are unable to receive the control characteristic values sent from the display unit, the functions of the control units cannot be controlled. Japanese Laid-Open Patent Publication No. 10-264739 reveals a process for performing the function of a control unit, using substitute or default control characteristic values stored in a ROM of the control unit, in the event of a communication failure. However, such a system becomes costly overall due to the added cost of the ROM.